<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>原生事件绑定</title>
  </head>
  <body>
    <button id="btn1">按钮1</button>
    <button id="btn2">按钮2</button>
    <button onclick="demo()">按钮3</button>

    <script>
      const btn1 = document.getElementById('btn1')
      btn1.addEventListener('click', () => {
        alert('btn1被点击了')
      })

      const btn2 = document.getElementById('btn2')
      btn2.onclick = () => {
        alert('btn2被点击了')
      }

      function demo() {
        alert('btn3被点击了')
      }
    </script>
  </body>
</html>
